Drying kinetics of Pleurotus eryngii slices during hot air drying

Abstract

Hot air drying is widely adopted to extend the shelf life of Pleurotus eryngii, which is an edible fungus with high nutritional value and large market demand. Understanding moisture transfer during hot air drying is essential for both quality improvement and energy-efficient dryer design. In this study, we investigated the drying kinetics of P. eryngii slices with different thicknesses (4, 8, and 12 mm) under different hot air temperature levels (40, 50, 60, 70, and 80°C) and a constant air velocity (2 m/s). It is found that the drying rate increases with the increase of the hot air temperature or the decrease of the thickness of P. eryngii slices. Only a falling rate period was observed during the hot air drying. We used eight mathematical models to describe the drying kinetics of P. eryngii slices and found that the logarithmic model fits the experimental data best. The fitted effective moisture diffusivity of P. eryngii slices is in the range of 3.34 × 10-9 to 2.25 × 10-9 m2/s, and the fitted drying activation energy is 19.30 kJ/mol, agreeing with the results in the literature. Additionally, we noticed that the color of dried P. eryngii slices becomes darker with the increase of hot air temperature due to the Maillard browning reaction. This study helps to understand the drying kinetics of P. eryngii slices during the hot air drying and guides the drying process optimization.